The invention relates to an electronic endoscope with a picture sensor located at its distal end and with several illumination units integrated in the endoscope, for producing illumination light irradiated at the distal endoscope end.
With such an electronic endoscope (DE 296 13 103 U1, DE 298 12 048 U1) e.g. in cancer diagnosis, photosensitive substances which are accumulated in the body may be stimulated by way of stimulation light for the fluorescence irradiation. The fluorescence stimulation may be carried out with LEDs producing single-colored light, e.g. blue, green or red light, illumination units in combination with a black and white CCD chip as a picture sensor with dichroitic filters. With the known electronic endoscope known from the above publication the LEDs serving the illumination are arranged at the distal endoscope end. On account of the constructional size of the LEDs, the outer diameter of the endoscope increases disadvantageously.
Generally electronic endoscopes beyond the early primary field of application of diagnosis are also applied in surgery, in particular minimalinvasive surgery, with which the operation field may be shown on a monitor for the whole operating team.
With a typical endoscope used in minimal-invasive surgery at the proximal end thereof via an objective a camera head is adapted. This is connected to a camera controller which converts the signals coming from the camera head into a picture which can be displayed on a monitor. The illumination light is supplied from the outside and moves from a light source via a fiber-optic to a light exit at the distal end of the endoscope. This arrangement however has the disadvantage that the camera head must be adapted onto the proximal end of the endoscope via an objective. This has considerable ergonomic disadvantages since the dimensions of the head and objective only permit a miniaturization to a limited extent.
Furthermore the picture definition with each change in endoscope must be manually adapted at the objective. By way of the numerous air-glass transitions in the endoscope, in the objective and in the camera head, with the picture brightness there occurs losses. With the use of endoscopes of various diameters the picture size must be compensated at the monitor by the use of objectives of differing focal distances, or a zoom objective must be used. This however compared to an objective with a fixed focal distance has larger dimensions and a higher weight which in turn has a disadvantageous effect on the ergonomics.
The electronic endoscopes common in the meantime with the advancing development of semiconductor technology are distinguished in that the picture sensor is no longer arranged proximally but distally in the endoscope. This has the result that all manual corrections with respect to the picture definition and focal length adaptation are done away with and occurring losses of the picture brightness are reduced on account of the low number of optical components. The handling is improved by the small dimensions of a proximally arranged plug, and the objective for camera adaptation necessary with the previously described endoscope may be done away with.
With a known embodiment form of such an electronic endoscope illumination light from an external light source via a fiber-optic bundle is coupled into the endoscope. At the proximal end of the electronic endoscope there is mounted a connection plug which permits a separation of the electronic endoscope from the connection cable leading to the camera controller. This has the advantage that for several electronic endoscopes only one connection cable type is required, which increases the economic efficiency of the system.
According to experience this connection cable from the electronic endoscope to the camera controller, on account of its mechanical loading, causes the greatest breakdown rate in the whole system. For this reason also for this, the separability of the connection cable from the electronic cable has shown to be advantageous, since by way of the exchangeability of the connection cable by the personnel on location, the running costs are reduced and the endoscope with a failure or breakage of the cable does not have to be sent back to the manufacturer for repair.
A disadvantage of such an endoscope is however the fact that the fiber-optic connection is no longer rotatable to the position of the picture sensor. In comparison to this with the firstly described endoscope with a proximally attached video camera, by way of rotating the camera head or the objective, the position of the picture on the monitor may be corrected such that the picture is no longer displayed on the monitor head first. Thus the fiber-optic connection with this endoscope by rotation of this endoscope may be brought into a favorable position without the picture on the monitor being shown in the wrong position.
With an endoscope system a rotation of the electronic endoscope compellingly has the consequence of a rotation of the picture on the monitor. This means that the endoscope must be located in a certain position in order to represent the picture in the correct position on the monitor. Under certain conditions this fact may lead to problems, since the endoscope, according to application, is not always located in the same position and on account of the forces which are exerted by the fiber-optic onto the endoscope, may be undesirably rotated which simultaneously means a rotation of the picture on the monitor. This may lead to the fact that the surgeon loses the orientation, since the operating region is no longer shown on the monitor in the correct position.
With a further known endoscope the actual electronic endoscope including the fiber-optic and the connection cable form one unit. The fiber-optic integrated in this unit, from the distal end of the endoscope up to the other end, of the fiber-optic, which is located in the light source, is designed without interruption as one piece. This has the advantage that by way of this no additional light losses arise at a coupling location between the fiber-optic and endoscope and thus a maximum of illumination light is guided further to the distal end. This embodiment form although improving the handling with regard the rotating of the endoscope, is however not yet optimal since the integrated fiber-optic cable and the camera cable are relatively heavy and thus increase the total weight of the system.
Furthermore with this known embodiment form of an electronic endoscope cable breakage is of a great disadvantage. If specifically the fiber-optic cable or the camera cable is defective, a repair at the place of the manufacturer is necessary, since on location the cable may not be professionally repaired or replaced. In the factory of the manufacturer the endoscope unit under certain circumstances must be completely disassembled for the repair. By way of this the running costs are increased and the interruption times are lengthened.